1. Field of Disclosure
The present invention relates to a manufacturing method of a liquid crystal display.
2. Description of the Related Art
A liquid crystal display is one of the most widely used types of a flat panel display, and includes two display panels in which field generating electrodes, such as pixel electrodes and a common electrode, are provided, and a liquid crystal layer interposed between the two display panels. In the liquid crystal display, a voltage is applied to the field generating electrodes to generate an electric field in the liquid crystal layer, and the orientation of liquid crystal molecules of the liquid crystal layer is determined and the polarization of incident light is controlled by the generated electric field to display an image.
Inside the display panels, an alignment layer for aligning the liquid crystal molecules of the liquid crystal layer is formed. When a voltage is not applied to the field generating electrode, the liquid crystal molecules are aligned in a defined direction by the alignment layer, whereas when a voltage is applied to the field generating electrode, the liquid crystal molecules are rotated along a direction of the electric field.
For such alignment of the liquid crystal, there has been adopted a rubbing process in which a polymer alignment layer is formed and the alignment layer is rubbed so as to be aligned with a rotating roller which is wrapped with a rubbing cloth made of nylon or rayon while the rotating roller is rotated at a high speed. However, the rubbing process may create scratches on a surface of a liquid crystal alignment agent due to mechanical rubbing, or generate high static electricity which leads to destruction of thin film transistors. Further, micro fibers released from the rubbing cloth may cause defects, which become a barrier to improvement in production yield.
To overcome the problems with the rubbing process and achieve innovation in the aspect of production yield, there has been derived a liquid crystal alignment method using a light such as UV radiation (hereinafter, referred to as “photo-alignment”). Photo-alignment refers to the mechanism using a linearly polarized UV radiation to cause the photoreactive groups bonded to a defined photoreactive polymer to participate in a photoreaction and aligning the main chain of the polymer in a defined direction to form a photo-polymerized liquid crystal alignment layer with aligned liquid crystals.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.